La0．5Sr0．5MnO3纳米晶体的制备与电磁性能研究

以柠檬酸为络合剂，采用溶胶-凝胶（sol—gel）自燃烧方法制备了La0．5Sr0．5MnO3纳米晶体。使用FT-IR，DSC—TG，XRD，波导方法对反应、反应产物以及反应产物的电磁性能进行了研究。结果表明，在凝胶中，金属离子与柠檬酸以络合物的形式存在。凝胶在273℃基本完成自燃烧反应。生成的La0．5Sr0．5MnO3纳米晶体为钙钛矿结构，随着反应温度的提高，产物的粒径逐渐增大。电磁性能结果表明，La0．5Sr0．5MnO3在8GHz～12GHz的微波范围内具有明显的介电损耗。随着厚度的增加，混合媒质的反射率逐渐增加，反射率吸收峰随着厚度的增加向低频移动。

Synthesis and Electromagnetic Property of La0.5Sr0.5MnO3 Nano Crystalline

La0.5Sr0.5MnO3 nano crystalline was synthesized by sol-gel auto-combustion method using citric acid as the chelating agents. Some analysis methods, which consisted of FT-IR, XRD, DSC-TG, wave-guide, were used to character the gel and the products after calcining. It was shown that metal ions and carboxyl were coordinated by the orientated manner. The phenomenon of melt, combustion and forming crystal for gel were observed in the process of thermo-decomposition, the nano crystalline had a dielectric loss in the frequency range of measurement. With the increasing of thickness, the reflectivity of perovskite-type nano crystalline increased and absorption peak shifted from high frequency to low frequency.